PharoGs Strawman 1 Phase 2: bootstrap from Minimal PharoGs Image packages directly

[dalehenrich]

The goal of this phase is to get to the point where PharoGs can be bootstrapped from https://github.com/pharo-project/pharo packages directly. This implies that the PharoMods be converted to common code in some form or moved into PharoGs specific packages.

• merge/reconcile PharoMods into https://github.com/pharo-project/pharo
• update PharoGs bootstrap scripts to load from https://github.com/pharo-project/pharo